US5511374A - High pressure air source for aircraft and engine requirements - Google Patents

Abstract

A method and apparatus for supplying cooling air on vehicles such as high speed aircraft includes diverting high pressure air from the compressor section of a gas turbine engine, cooling this air in a heat exchanger, compressing the air and subsequently cooling the air in a second heat exchanger to provide cooled, high pressure air. One embodiment additionally provides cooled air at relatively medium pressure and relatively low pressure, while the alternate embodiment additionally provides cooled air at relatively low pressure.

Description

This is a division of application Ser. No. 08/189,569, filed in Jan. 31, 1994 (U.S. Pat. No. 5,452,573).

FIELD OF THE INVENTION

This invention relates to a method and apparatus for generating cool air at differing pressures, including relatively high pressure, for meeting the cooling requirements, and other requirements of aircraft components and/or engine components.

BACKGROUND OF THE INVENTION

Survivability and structural requirements in advanced aircraft require cooling and thermal management of aircraft and propulsion structures. Additionally, some applications of aircraft technology, particularly those applications on supersonic aircraft, require sources of cooled, high pressure air. Conventional methods for propulsion system cooling in current aircraft engines typically employ either engine fuel, or air from one of the various sources in the propulsion system as a coolant. Among the traditional sources of cooling air are 1) ram air from the inlet, 2) air from the fan (in turbofan engines), or 3) air from the high compressor.

These sources for cooling air have generally been adequate for cooling aircraft components up to this time, the cooling air being primarily used for maintaining structural integrity of engine components. Although cooling air diverted from the aforementioned sources impacts overall engine performance, the cooling requirements have heretofore been achieved with only minimal impact on engine performance. However, as the amount of electronic and other heat generating equipment carried on aircraft has increased, the requirement for cooling system capability has correspondingly increased. In addition, as aircraft speeds and capabilities increase beyond about Mach 3, the demands on the cooling systems of aircraft increase as well. These increased speeds and capabilities require cooling of aircraft components such as leading edges of the airframe, and certain parts of the engine exposed to high temperature combustion products. Additionally, new uses of cool, high pressure air on aircraft increase the demand for such air beyond that amount that is currently available. The increasingly stringent requirements for future vehicle/engine systems will require improved sources of low temperature coolants.

What is needed is a method for producing cooled air at relatively high pressure, and at other relatively lower pressure as needed by the aircraft components and engines without substantially increasing the amount of cooling air diverted from the traditional sources of cooling air.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a method for increasing the production of cooled, relatively high pressure air for vehicle components, and engine components of the vehicle.

Another object of the present invention is to provide a method for increasing the cooling capability for aircraft components and engines without substantially increasing the amount of cooling air diverted from the traditional sources of cooling air.

According to the present invention a method and apparatus are disclosed that provide for supplying cooling air on vehicles such as high speed aircraft. The method includes diverting high pressure air from the compressor section of a gas turbine engine, cooling this air in a heat exchanger, compressing the air and subsequently cooling the air in a second heat exchanger to provide cooled, high pressure air. One embodiment additionally provides cooled air at relatively medium pressure and relatively low pressure, while the alternate embodiment additionally provides cooled air at relatively low pressure.

The foregoing and other features and advantages of the present invention will become more apparent from the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the components of the first embodiment of the apparatus of the present invention for a vehicle powered by a turbofan gas turbine engine.

FIG. 2 is a schematic view of the components of the second embodiment of the apparatus of the present invention for a vehicle powered by a turbofan gas turbine engine.

DETAILED DESCRIPTION OF THE INVENTION

The method and apparatus of the present invention is for generating cooled air for cooling components of aircraft vehicles that incorporate large amounts of heat generating equipment on board, or have other requirements for pressurized cool air, such as may exist for ahigh speed vehicle 10, such as an aircraft that flies at supersonic speeds in excess of Mach 3. FIG. 1 illustrates a concept for the primary purpose of providing high pressure air, with no specific cooling requirement. This concept provides capability for producing cooled high pressure air, with air flow rates varying over a wide range, in response to aircraft requirements. Practicing this invention requires at least onegas turbine engine 12 in the vehicle, such as the engine shown in FIG. 1.

Theengine 12, which is preferably a turbofan, includes, in serial flow arrangement, anengine inlet section 14 for receiving ambient air and delivering the ambient air to thecompressor section 18, andaft 16 of theinlet section 14 is thecompressor section 18 for compressing the ambient air thereby producing compressedair 22 at a first pressure. Thecompressor section 18 has, in serial flow arrangement, a low pressure compressor, or "fan" 82, and ahigh pressure compressor 84. Thehigh pressure compressor 84 is for compressing air received from thelow compressor 82 at the first pressure to produce compressed air at a second pressure. Thehigh pressure compressor 84 has an exit stage bleed 100 for extracting air therefrom at a bleed pressure essentially equal to the second pressure. Aft of thecompressor section 18 is acombustor section 24 for mixing fuel with thecompressed air 22 and igniting the fuel and compressedair 22 to producecombustion products 26. Aft of thecombustion section 24 is aturbine section 28 for expanding thecombustion products 26 and driving thecompressor section 18. Theturbine section 28 of the turbofan 80 has in serial flow arrangement, ahigh pressure turbine 86 and alow pressure turbine 88. Thelow pressure turbine 88 drives thefan 82 via thelow shaft 90 which connects thelow pressure turbine 88 to thefan 82, and thehigh pressure turbine 86 drives thehigh compressor 84 via thehigh shaft 92 which connects thehigh pressure turbine 86 to thehigh compressor 84. Aft of theturbine section 28 is anexhaust section 32 for conveying thecombustion products 26 from theturbine section 28, through thenozzle 20, and out of the aft end of thegas turbine engine 12. Abypass duct 200 extends between theexhaust section 32 and the outlet of thelow compressor 82 to permit compressed air exiting the low compressor to bypass around the high compressor, thecombustor section 24 andturbine section 28.

Thevehicle 10 also includes first 40 and second 41 heat exchangers located in thebypass duct 200, as shown in FIG. 1. Each of theheat exchangers 40, 41 is preferably "doughnut" shaped, extending radially about the radiallyinner wall 201 of thebypass duct 200. Thesecond heat exchanger 41 is located between thefirst heat exchanger 40 and thelow pressure compressor 82, so that thesecond heat exchanger 41 is upstream of thefirst heat exchanger 40 relative to the flow of compressedair 22 flowing through thebypass duct 200 from theexit 43 of thelow compressor 82. Each of theheat exchangers 40, 41 has first 123, 124 and second 120, 121 flow paths extending therethrough, and each flow path has an inlet and an outlet. The first flow path of each heat exchanger is exposed to thecompressed air 22 exiting the low compressor, and it is thiscompressed air 22 which is the coolant for the first andsecond heat exchangers 40, 41.

The present invention also has anauxiliary unit 36 which includes anauxiliary compressor 50 and anauxiliary turbine 52, and theauxiliary turbine 52 is connected to theauxiliary compressor 50 by anauxiliary shaft 54 to provide power thereto. Theauxiliary compressor 50 has acompressor inlet port 60 and acompressor discharge port 61, and the auxiliary turbine likewise has aturbine inlet port 62 and aturbine discharge port 63.

Afirst conduit 70 connects exit stage bleed of the high pressure compressor to theturbine inlet port 62, and asecond conduit 71 connects thecompressor discharge port 61 to theinlet 110 of thesecond flow path 120 of thefirst heat exchanger 40. As used herein, the word "connect" when used in relation to the conduits means that the conduit provides a path for the flow of air between each of the elements to which a particular conduit is connected. As shown in FIG. 1, thesecond conduit 71 includes athrottle valve 72 therein, the purpose of which is discussed in greater detail below. Athird conduit 73 is connected to thesecond conduit 71 between thethrottle valve 72 and theinlet 110 to thesecond flow path 120 of thefirst heat exchanger 40, and thethird conduit 73 is also connected to thefirst conduit 70 to receive compressed air therefrom. Afourth conduit 74 connects the outlet 111 of thesecond flow path 120 of thefirst heat exchanger 40 to thecompressor inlet port 60, and afifth conduit 75 connects theinlet 115 of thesecond flow path 121 of thesecond heat exchanger 41 to thesecond conduit 71. Thefifth conduit 75 is connected to thesecond conduit 71 between thethrottle valve 72 and thecompressor discharge port 61, and thefifth conduit 75 preferably includes aflow control valve 76 therein. Asixth conduit 77 is connected to theturbine discharge port 63, and is also connected to acomponent 300 that can utilize cool air that is at relatively low pressure, and preferably is at ambient pressure so that the maximum amount of energy that can be extracted from the compressed air expanding through theauxiliary turbine 52 is extracted to drive theauxiliary compressor 50. Aseventh conduit 78 is connected to theoutlet 116 of thesecond flow path 121 of thesecond heat exchanger 41, and theseventh conduit 78 is connected tocomponents 301 that utilize relatively high pressure cool air.

In operation some of thecompressed air 22 exiting thelow pressure compressor 82 at a first, known pressure is diverted into thebypass duct 200 and flows through thefirst flow path 123, 124 of the first andsecond heat exchangers 40, 41, and this compressed air is the coolant for theheat exchangers 40, 41. A portion of the compressed air from thehigh pressure compressor 84 is diverted therefrom through the exit stage bleed 100 at a second pressure significantly higher than the first pressure, and as those skilled in the art will readily appreciate, the compressed air bled from thehigh pressure compressor 84 is at a significantly higher temperature than the compressed air exiting thelow pressure compressor 82. The portion bled from thehigh pressure compressor 84 is then split into a first part which is routed to theturbine inlet port 62, and a second part that is routed to theinlet 110 of thesecond flow path 120 of thefirst heat exchanger 40 via the third 73 and second 71 conduits, and introduced into thesecond conduit 71 between thethrottle valve 72 and theinlet 110 to thesecond flow path 120 of thefirst heat exchanger 40, as shown in FIG. 1. The first part of the portion bled from thehigh pressure compressor 84 is expanded through theauxiliary turbine 52, thereby producing cooled, relatively low pressure air for cooling components of the vehicle, and providing work to drive the auxiliary compressor via theauxiliary shaft 54.

The second part of the portion flows into theinlet 110 of thesecond flow path 120 of thefirst heat exchanger 40, flows through thesecond flow path 120 thereof and out of the outlet 111 thereof while some of the compressed air from the low compressor flows through thefirst flow path 123 of thefirst heat exchanger 40, thereby cooling the second part. The second part exiting the outlet 111 of thesecond flow path 120 of thefirst heat exchanger 40 is then delivered to thecompressor inlet port 60 and compressed to a higher pressure in theauxiliary compressor 50, so that the second part exits theauxiliary compressor 50 through thedischarge port 61 thereof at a third pressure significantly higher than the second pressure.

A first amount of the second part of compressed air, which first amount may be some or all of the compressed air exiting theauxiliary compressor 50 at the third pressure, is recirculated through thefirst heat exchanger 40 by bleeding the first amount through thethrottle valve 72. The recirculated compressed air is cooled again in thefirst heat exchanger 40 and then returns to the auxiliarycompressor inlet port 60 via thefourth conduit 74. Thethrottle valve 72 reduces the pressure of the first amount to a pressure essentially the same as the first pressure prior to recirculating the first amount through thesecond flow path 120 of thefirst heat exchanger 40.

A second amount of the second part of compressed air at the third pressure, which may be some or all of the compressed air exiting the auxiliarycompressor discharge port 61, is diverted through theflow control valve 76 in thefifth conduit 75 to thesecond heat exchanger 41 where it is cooled. Theflow control valve 76 is used to selectively modulate the flow of the second amount of the second part of compressed air at the third pressure from thesecond conduit 71 through thefifth conduit 75 to theinlet 115 of thesecond flow path 121 of thesecond heat exchanger 41. The second amount then flows into theinlet 115 of thesecond flowpath 121 of thesecond heat exchanger 41 and through thesecond flow path 121 thereof while some of the compressed air from thelow compressor 82 is flowing through thefirst flow path 124 thereof, cooling the second amount at the third pressure, thereby producing cooled, relatively high pressure air for cooling components of thevehicle 10. As air is diverted from therecirculating compressor loop 71, 120, 74 through theflow control valve 76, the diverted air is replaced by air bled from the engine high pressure compressor through theexit stage bleed 100. It must be understood that in this concept, the compressed air at stations in thethird conduit 73 and in thesecond conduit 71 between thethrottle valve 72 and theinlet 110 of thesecond flow path 120 of thefirst heat exchanger 40, as well as the air within thesecond flow path 120 of thefirst heat exchanger 40 are at the pressure of the engine high pressure compressor exit stage bleed 100 pressure, while the air in thefifth conduit 75, thesixth conduit 78, and thesecond flow path 121 of thesecond heat exchanger 41 are at a substantially higher pressure, based on the overall pressure ratio increase of theauxiliary compressor 50. The air in thesixth conduit 77 is cool and at relatively low pressure, and can be returned to the engine exhaust system, or dumped into an appropriate low pressure region of the aircraft. The relatively high pressure air exiting thesecond flow path 121 of thesecond heat exchanger 41 can be used for aircraft requirements, or a portion of this air can be used for cooling high pressure regions of theaircraft engine 12, such as compressor or turbine components, thus allowing improved performance and or durability of the engine components.

FIG. 2 illustrates an alternate embodiment of the present invention in which provision is made to supply a range of air sources at various pressures and temperatures, for satisfying a supersonic aircraft's environmental control requirements, providing general cooling to the various thermal management systems, and supplying high pressure air for aircraft attitude or aerodynamic control. As FIG. 2 shows, the elements of theturbofan 12 are the same as those shown for theturbofan 12 in FIG. 1, except that in addition to theexit stage bleed 100, theturbofan 12 of the alternate embodiment also includes an interstage bleed 101. Otherwise, the reference numerals in FIG. 2 represent the same elements as they represented in FIG. 1.

Thevehicle 10 also includes first andsecond heat exchangers 40, 41 located in thebypass duct 200, as shown in FIG. 2, and each of theheat exchangers 40, 41 is similar to those described in the preferred embodiment. However, in the alternate embodiment, thefirst heat exchanger 40 is located between thesecond heat exchanger 41 and thelow pressure compressor 82, so that thefirst heat exchanger 40 is upstream of thesecond heat exchanger 41 relative to the flow ofcompressed air 22 flowing through thebypass duct 200 from theexit 43 of the low compressor.

Theauxiliary unit 37 of the alternate embodiment includes anauxiliary compressor 50 having acompressor inlet port 60 and acompressor discharge port 61, a firstauxiliary turbine 52 having a firstturbine inlet port 62 and a firstturbine discharge port 63, and a secondauxiliary turbine 53 having a secondturbine inlet port 64 and a secondturbine discharge port 65. The first and secondauxiliary turbines 52, 53 are connected to theauxiliary compressor 50 by anauxiliary shaft 54 to provide power thereto, as shown in FIG. 2. Theauxiliary unit 37 also includes aselector valve 250, and afirst conduit 251 connects the exit stage bleed 100 to theselector valve 250, and asecond conduit 252 connects the interstage bleed 101 to theselector valve 250. Athird conduit 253 connects theselector valve 250 to theinlet 210 of thesecond flow path 220 of thefirst heat exchanger 40, and afourth conduit 254 connects theoutlet 211 of thesecond flow path 220 of thefirst heat exchanger 40 to thecompressor inlet port 60. Afifth conduit 255 connects thecompressor discharge port 61 to theinlet 215 of thesecond flow path 221 of thesecond heat exchanger 41, and asixth conduit 256 connects theoutlet 216 of thesecond flow path 221 of thesecond heat exchanger 41 to thefirst inlet port 62 of thefirst turbine 52. Aseventh conduit 257 connects thesixth conduit 256 tocomponents 301 that utilize cool, relatively high pressure air, and aneighth conduit 258 connects the firstturbine discharge port 63 to the secondturbine inlet port 64. A ninth conduit 259 connects theeighth conduit 258 tocomponents 302 that utilize cool, relatively medium pressure air, and a tenth conduit 260 connects the secondturbine discharge port 65 tocomponents 300 that utilize cool, relatively low pressure air. Additionally, thefourth conduit 254 includes a firstflow control valve 261 therein, theseventh conduit 257 includes a secondflow control valve 262 therein, the ninth conduit 259 includes a third flow control valve 263 therein, and the tenth conduit 260 includes a fourthflow control valve 264 therein.

In operation, some of the compress air exiting thelow pressure compressor 82 at a first known pressure is diverted into thebypass duct 200 and flows through thefirst flow path 123, 124 of the first andsecond heat exchangers 40, 41. Theselector valve 250 is used to divert a portion of compressed air from thehigh compressor 84 through either the interstage bleed 101 or theexit stage bleed 100, depending on the current requirements for cool air on thevehicle 10. Compressed air diverted from theexit stage bleed 100 is at a second pressure that is significantly greater than the first pressure, while compressed air diverted from the interstage bleed 101 is at a third pressure that is greater than the first pressure but less than the third pressure. The flow of the portion into thefourth conduit 254 is initiated by opening the firstflow control valve 261. This portion then flows into theinlet 210 of thesecond flow path 220 of thefirst heat exchanger 40 and out of theoutlet 211 thereof while some of the compressed air from thelow compressor 82 flows through thefirst flow path 123 of thefirst heat exchanger 40, thereby cooling thesecond flow path 220 thereof and the diverted portion of compressed air.

The diverted portion of compressed air is then compressed to a greater pressure by delivering the portion exiting theoutlet 211 of thesecond flow path 220 of thefirst heat exchanger 40 to thecompressor inlet port 60 through thefourth conduit 254 and compressing the portion in theauxiliary compressor 50. The portion then exits theauxiliary compressor 50 through thecompressor discharge port 61 into thefifth conduit 255 at a fourth pressure significantly higher than the second pressure. The portion is then cooled at the fourth pressure by flowing the portion exiting thecompressor discharge port 61 into theinlet 215 of thesecond flow path 22 1 of thesecond heat exchanger 41 and through thesecond flow path 221 thereof. Since thefirst flow path 124 of thesecond heat exchanger 41 is simultaneously being cooled by the compressed air at the first pressure flowing through thefirst flow path 124 thereof, the portion of compressed air is cooled at the fourth pressure, thereby producing cooled, relatively high pressure air which flows into thesixth conduit 256. The flow of this cooled, relatively high pressure air through theseventh conduit 257 to thecomponents 301 of thevehicle 10 is controlled by the secondflow control valve 262, as shown in FIG. 2. A first part of the portion is delivered to the firstturbine inlet port 62 and expanded through the firstauxiliary turbine 52, providing work to drive theauxiliary compressor 50 via theauxiliary shaft 54 and simultaneously reducing the temperature of the first part exiting thefirst discharge port 63 thereof. The flow of the first part into thefirst turbine 52 is preferably controlled and directed by variableinlet guide vanes 400, of the type known in the art, to maximize the efficiency of the work produced by the expanding first part. The flow rate and efficient expansion of air in theauxiliary turbines 52, 53 is controlled by these variable geometryinlet guide vanes 400, 401. These control features are applications of existing technology, and therefore are beyond the scope of the present invention.

The first part exiting thefirst discharge port 63 is cooled, relatively medium pressure air which flows into theeighth conduit 258. If thevehicle 10 has a current requirement for such cooling air, the third flow control valve 263 is opened, and cooled, relatively medium pressure air flows to thosecomponents 302 of thevehicle 10 requiring such cooling air. If there is no current need for such air, or such need does not require all of such air, a first amount of the first pan is delivered to the secondturbine inlet port 64 via theeighth conduit 258. As those skilled in the art will readily appreciate, due to the high air pressure of the air exiting thesecond flow path 221 of thesecond heat exchanger 41 and the very large potential pressure ratio between such air and the external ambient air, two stages of expansion may be necessary (with current technology radial-inflow-turbines) to fully utilize the expansion work potential, and corresponding refrigeration potential of such air. The flow of the air entering the secondauxiliary turbine 53 is likewise controlled and directed by variableinlet guide vanes 401, and the first amount is expanded through the secondauxiliary turbine 53, providing work to drive theauxiliary compressor 50 via theauxiliary shaft 54 and reducing the temperature of the first amount exiting thesecond discharge port 65 thereof. The air exiting the secondturbine discharge port 65 is cooled, relatively low pressure air which flows into the tenth conduit 260 tocomponents 300 of thevehicle 10 requiring such air, or else this air is dumped overboard. The flow of such air through the tenth conduit 260 is controlled by the fourthflow control valve 264.

Although this invention has been shown and described with respect to a detailed embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.

Claims (12)

We claim:

1. A method for producing cooled air at relatively high, medium, and low pressures for use with components of a vehicle, said method comprising:

providing at least one gas turbine engine in said vehicle, said engine having in serial flow arrangement a low pressure compressor and a high pressure compressor, said low pressure compressor for compressing ambient air to produce compressed air at a first pressure and said high pressure compressor for compressing air at said first pressure to produce compressed air at a second pressure, said high pressure compressor having an interstage bleed for extracting air therefrom at a third pressure significantly greater than the first pressure and significantly less than the second pressure and said high pressure compressor having an exit stage bleed for extracting air therefrom at a bleed pressure essentially equal to the second pressure;

diverting a portion of said compressed air from said high pressure compressor through one of said bleeds;

cooling the portion in a cooled flow path that is cooled with some of said compressed air at said first pressure;

compressing the portion to a fourth pressure significantly higher than said second pressure;

cooling said portion at said fourth pressure, thereby producing cooled, relatively high pressure air for cooling components of said vehicle;

expanding a first pan of said portion, thereby producing cooled, relatively medium pressure air for cooling components of said vehicle; and,

expanding a first amount of said first part, thereby producing cooled, relatively low pressure air for cooling components of said vehicle.

2. The method of claim 1 wherein the gas turbine engine includes, in serial flow arrangement with the high pressure compressor, a combustor section for mixing fuel with said compressed air at said second pressure and igniting said fuel and compressed air at said second pressure to produce combustion products, a turbine section for expanding said combustion products and driving the low and high pressure compressors, an exhaust section for conveying said combustion products from said turbine section and out of said gas turbine engine, a bypass duct extending between the low pressure compressor and the exhaust section for bypassing compressed air exiting the low compressor around the high pressure compressor, the combustor section and the turbine section, and first and second heat exchangers located in said bypass duct, each heat exchanger having first and second flow paths extending therethrough, the second flow path of the first heat exchanger defining said cooled flow path, each flow path having an inlet and an outlet, said first flow path of each heat exchanger exposed to some of said compressed air at said first pressure, and the step of diverting a portion of said compressed air from said high pressure compressor includes

diverting said some of said compressed air from said low pressure compressor into the bypass duct and flowing said some of said compressed air through the first flow path of the first and second heat exchangers.

3. The method of claim 2 wherein the step of diverting a portion of said compressed air from said high pressure compressor through one of said bleeds is preceded by the step of:

providing an auxiliary unit in said vehicle, said auxiliary unit including an auxiliary compressor having a compressor inlet port and a compressor discharge port, a first auxiliary turbine having a first turbine inlet port and a first turbine discharge port, and a second auxiliary turbine having a second turbine inlet port and a second turbine discharge port, said first and second auxiliary turbines connected to said auxiliary compressor by a shaft to provide power thereto.

4. The method of claim 3 wherein the step of cooling the portion in a cooled flow path includes

flowing the portion into the inlet of the second flow path of the first heat exchanger and out of the outlet of the second flow path thereof while flowing said some of said compressed air through said first flow path thereof, thereby cooling said portion.

5. The method of claim 4 wherein the step of compressing the portion to a fourth pressure significantly higher than said second pressure includes

delivering said portion exiting the outlet of the second flow path of the first heat exchanger to the compressor inlet port and compressing said portion in said auxiliary compressor, said portion exiting said auxiliary compressor through said compressor discharge port at a fourth pressure significantly higher than said second pressure.

6. The method of claim 5 wherein the step of cooling said portion at said fourth pressure includes

flowing said portion exiting the compressor discharge port into the inlet of the second flowpath of the second heat exchanger and through the second flow path thereof while cooling said portion with said some of said compressed air flowing through the first flow path thereof, cooling said portion at said fourth pressure, thereby producing cooled, relatively high pressure air for cooling components of said vehicle.

7. The method of claim 6 wherein the step of expanding a first part of said portion includes delivering a first part of said Portion to said first turbine inlet port and expanding said first part through said first auxiliary turbine, thereby providing work to drive the auxiliary compressor via said shaft, reducing the temperature of the first part exiting the first discharge port thereof, and producing cooled, relatively medium pressure air for cooling components of said vehicle.

8. The method of claim 7 wherein the step of expanding a first amount of said first part includes delivering a first amount of said first part exiting the first turbine discharge port to said second turbine inlet port and expanding said first amount through said second auxiliary turbine, providing work to drive the auxiliary compressor via said shaft and reducing the temperature of the first amount exiting the second discharge port thereof, thereby producing cooled, relatively low pressure air for cooling components of said vehicle.

9. The method of claim 8 wherein the first heat exchanger is located between said second heat exchanger and said low pressure compressor.

10. The method of claim 9 wherein said vehicle is a supersonic aircraft.

11. An apparatus for producing cooled air at relatively high, medium, and low pressures for use with components of a vehicle, said apparatus comprising

a gas turbine engine having in serial flow arrangement a low pressure compressor and a high pressure compressor for compressing ambient air thereby producing compressed air, a combustor section for mixing fuel with said compressed air and igniting said fuel and compressed air to produce combustion products, a turbine section for expanding said combustion products and driving the low and high pressure compressors, an exhaust section for conveying said combustion products from said turbine section and out of said gas turbine engine, said high pressure compressor having an interstage bleed for extracting air therefrom at a bleed pressure significantly greater than the first pressure and significantly less than the second pressure, said high pressure compressor having an exit stage bleed for extracting air therefrom at a bleed pressure essentially equal to the second pressure, and said engine having a bypass duct extending between the low pressure compressor and the exhaust section for bypassing compressed air exiting the low pressure compressor around the high compressor, combustor section and turbine section;

first and second heat exchangers located in said bypass duct, said first heat exchanger located between said second heat exchanger and said low pressure compressor, each heat exchanger having first and second flow paths extending therethrough, each flow path having an inlet and an outlet, said first flow path of each heat exchanger exposed to the compressed air exiting the low pressure compressor; and,

an auxiliary unit including an auxiliary compressor having a compressor inlet port and a compressor discharge port, a first auxiliary turbine having a first turbine inlet port and a first turbine discharge port, a second auxiliary turbine having a second turbine inlet port and a second turbine discharge port, said first and second auxiliary turbines connected to said auxiliary compressor by a shaft to provide power thereto, a selector valve, a first conduit connecting said exit stage bleed to the selector valve, a second conduit connecting said interstage bleed to the selector valve, a third conduit connecting the selector valve to the inlet of the second flow path of the first heat exchanger, a fourth conduit connecting the outlet of the second flow path of the first heat exchanger to the compressor inlet port, a fifth conduit connecting the compressor discharge port to the inlet of the second flow path of the second heat exchanger, a sixth conduit connecting the outlet of the second flow path of the second heat exchanger to the first inlet port of the first turbine, a seventh conduit connecting the sixth conduit to components that utilize cool, relatively high pressure air, an eighth conduit connecting the first turbine discharge port to the inlet of the second turbine inlet port, a ninth conduit connecting the eighth conduit to components that utilize cool, relatively medium pressure air, and a tenth conduit connecting the second turbine discharge port to components that utilize cool, relatively low pressure air.

12. The apparatus of claim 11 wherein said fourth conduit includes a first flow control valve therein, said seventh conduit includes a second flow control valve therein, said ninth conduit includes a third flow control valve therein, and said tenth conduit includes a fourth flow control valve therein.

Images